This looks more like a caching solution to me, not a way to skip integration tests with your DB. I can't seem to find how you invalidate the saved interactions,

This looks more like a caching solution to me, not a way to skip integration tests with your DB. I can't seem to find how you invalidate the saved interactions, but I assume it must either detect changes or you manually clear the cache. This seems like a reasonable solution to speed up integration tests when you need to run them frequently. Particularly useful when adopting legacy code that that only supports integration testing due to poor design.